Controllable pitch tunnel thruster for ship positioning

ABSTRACT

A ship is described having a transverse thruster arranged in a tunnel running athwartship preferably, for example, near the bow so as to enhance steering or for slowly moving the ship sideways. The thruster comprises a movable portion of the tunnel wall having inwardly extending blades. The movable wall and blades are driven together in rotation about the axis of the tunnel so that the blades propel water therethrough. In addition, the pitch of the blades relative to a plane transverse to the tunnel axis is controllable for continuous variation of thrust from a maximum in one direction to a maximum in the opposite direction. Means are provided for controlling pitch of the blades while the thruster is rotating.

[H1 3,759,2H [451 Sept. 18, 1973 United States Patent n 1 Kuntz, Jr.

[ CONTROLLABLE PITCH TUNNEL Primary Examiner-Milton Buchler Assistant Examiner-Stuart M. Goldstein Attorney-Richard D. Seibel THRUSTER FOR SHIP POSITIONING [75] Inventor: Francis A. Kuntz, Jr., San Pedro,

Calif.

[73] Assignee: Global Marine, Inc., Los Angeles,

[57] ABSTRACT A sh is described having a transverse thruster arrlr- .mlmm w .W boa mm .1. fem mmh P 6 mm m n ranged in a tunnel running athwa example, near the bow so as to enh slowly moving the ship sideways.

l 7 9 l M n mam C01 0 N P un. FA 1] 21 22 ll.

prises a movable portion of the tunnel wall having inwardly extending blades. The mova 5- en d at .I e m f 30 X Ma 8 m b are driven together in rotation about nel so that the blades propel water therethrough. In addition, the pitch of the blades relative to a plane trans verse to the tunnel axis is controllable for continuous variation of thrust from a maximum in one direction to 82 4M4.) HS H 2 10 1 m ,2 42 4 .1 m I u. nus u 1 mm WWh c .r uni "2 s L o t d td UmF 1]] 218 555 [ll [56] References Cited UNITED STATES PATENTS a maximum in the opposite direction. Means are provided for controlling pitch of the blades while the thruster is rotating.

2,605,606 8/1952 415/122 A 2,153,055 4/1939 Weissmann.... 415/122 A 7 Claims, 5 Drawing Figures PATENTEU SEP 1 a ma SHEEI 1 BF 3 INVENTOR. [PA/V675 .4 4 04/72, ze.

CONTROLLABLE PITCH TUNNEL TI'IRUSTER FOR SHIP POSITIONING BACKGROUND In many situations on board ship it is desirable to have a transverse thruster near the bow in order to enhance the ability of the ship to turn in a short radius or to help hold the ship on a desired course. When such transverse thrusters are provided at both the bow and stern it is feasible to move a ship sideways in order to hold it on a station without rotation of the ship or forward thrusting. Transverse thrusters are also useful in docking a ship. Typically, transverse thrust is attained by mounting a screw in a tunnel running athwartship so that water is drawn in from one side of the ship and discharged from the opposite side. For optimum efficiency the transverse thruster is preferably mounted well below the water line to avoid ingesting air and near the bow for maximum steering effect. In many ships this is a very narrow portion so that the tunnel is relatively short. When a screw is mounted in the tunnel it is difficult to get power to it when a conventional hub is used. One technique mounts a screw in the center leg of a Z-shaped tunnel so that a drive shaft can be taken directly to the hub. In another arrangement a ring is employed around the outer ends of the blades and power is applied by pinion or bevel gear drives on the ring.

In either of these arrangements struts extend from the walls of the tunnel to a hub supported structure for keeping the screw centered in the tunnel. The struts reduce the efficiency of the screw and may cause cavitation, vibration or substantial flow resistance. Another difficulty with a transverse thruster has been that, to reverse thrust the direction of rotation of the screw is reversed so that what was the leading edge of the blade becomes the trailing edge. This requires reversing of the driving engine or at least a portion of the drive train which is necessarily slow and unsuitable for very quick maneuvering. Since the leading and trailing edges of the screw are reversed one is either faced with a screw that is relatively efficient in its forward direction and has less thrust in its reverse direction or a symmetrical screw which is of less than optimum efficiency in both directions of rotation.

BRIEF SUMMARY OF THE INVENTION Therefore, in practive of this invention according to a presently preferred embodiment there is provided a movable portion of a tunnel wall in the transverse thrust tunnel through a ship. Means are provided for rotating the movable portion of the tunnel wall about the tunnel axis. A plurality of blades extend inwardly from the movable portion of the tunnel wall and are connected therewith for rotation about the tunnel axis. Means are also provided for controlling the pitch of the blades relative to a plane transverse to the tunnel axis whereby the magnitude and direction of thrust can be varied without changing engine rotation.

DRAWINGS These and other features and advantages of the invention will be appreciated as the same becomes better understood by reference to the following detailed description of a presently preferred embodiment when consideredin connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary cutaway view of a ship bow having a transverse tunnel thruster constructed according to principles of this invention;

FIG. 2 is a transverse cross-section through the tunnel thruster;

FIG. 3 is a fragmentary longitudinal cross-section illustrating a differential drive mechanism for the tunnel thruster;

FIG. 4 illustrates schematically operation of the differential drive of FIG. 3; and,

FIG. 5 illustrates in longitudinal cross-section another embodiment of thruster drive and control mechanism.

DESCRIPTION FIG. 1 is a fragmentary and semi-schematic view of the bow 10 of the ship having a tunnel thruster constructed according to principles of this invention. As illustrated in this embodiment there is a transverse tunnel 11 below the water line of the ship and extending transverse to the length thereof. In the center of the tunnel 11 is a thruster 12 described and illustrated in greater detail hereinafter. Openings 13 extend through the sides of the ship to permit entrance and exit of water through the tunnel. Adjacent the openings 13 there are fixed tunnel walls 14 on either side of the thruster l2.

Between the two fixed wall portions 14 is a movable wall portion 16 that is substantially a continuation of the fixed wal portion with exceptions as hereinafter described for minimizing turbulence. A gear box 17 provides for rotation of the movable wall portion 16 about the axis of the tunnel and control of pitch of the thruster blades as described in greater detail hereinafter. A drive shaft 18 extends from the gear box to a conventional drive motor 19 which may be any of a variety of prime movers such as a turbine, diesel engine or electric motor as may be convenient for driving the transverse thruster. It will be recognized that the gear box 17 is illustrated on the lower side of the thruster 12 when in fact it may be preferable to mount it above or aft of the thruster to best fit within the structure of the ship and that the illustrated location is merely for convenience and clarity.

FIG. 2 comprises a cross-section through the center of the thruster looking along the length of the tunnel 13. In the preferred embodiment four blades 21 extend inwardly from the movable wall portion 16. Other numbers of blades may be used as desired. The blades 21 extend in cantilver fashion inwardly and are unsupported at their inner free ends. The length of the blades is such that they do not touch each other near the tunnel axis.

FIG. 3 illustrates a fragmentary crosssection taken along the length of the tunnel and illustrating the thruster and a portion of the control mechanism therefor. The thruster has a fixed ring 22 forming a segment of the tunnel wall and which is bolted to the principal tunnel wall 14 at a flange 20. Such a connection is provided so that the entire thruster assembly can be unbolted and removed from the tunnel for replacement or repair as may be required. A second flange 23 on the fixed ring connects to the gear case 17, only a portion of which is shown in FIG. 3. The gear case surrounds the operating mechanism for assuring lubrication thereof. Such a gear case may, for example, be maintained at a slight positive pressure in order to inhibit intrusion of sea water into the operating mechanisms. A second fixed ring M is at the opposite end of the thruster mechanism for connecting it to the wall of the tunnel 14.

Heavy duty ball bearings 26 support the movable wall portion 16 in the form of a ring between the fixed rings 22 and 24. This permits the entire ring 16 to rotate around the axis of the tunnel. A bevel gear 27 extends around the entire periphery of the movable ring 16 and engages with a drive bevel gear 28 connected to the drive shaft 18. Thus upon rotation of the drive shaft 18 the movable wall ring 16 is rotated for driving the tun nel thruster. Seals 29 between the fixed rings 22 adn 24 and the movable ring 16 inhibit the intrusion of sea water into the operating mechanisms or loss of grease from the gear case 17.

Each of the baldes 21 (two of which are seen in F163) is mounted on a circular blade support plate 31. Each blade support plate is mounted in a circular aperture in a side of the movable ring 16 by ball bearings 32. A seal 33 keeps sea water out and lubricant in. The blade support plates 31 are thus each rotatable about an axis lying in a plane normal to the axis of the tunnel. Since the blades are mounted on the blade support plates and extend inwardly toward the center of the tunnel, rotation of the blade support plate changes the pitch or angle of attack of the blade.

In the embodiment illustrated in FIG. 3 the blades 21 are merely shown as symmetrical since he detail design of the blades depends on size, operating speed, and the like and such design is well within the skill of the art. The blades can also be symmetrical from leading to trailing edge or can be asymmetrical as may be desired for optimum efficiency. It will be noted that the leading edge of the blades remains the leading edge despite change in direction of thrust since the blade can pass through a position with essentially zero thrust to positions of maximum thrust in either direction without reversing the direction or speed of rotation of the ring. Further if desired the propeller blades may have variable pitch between the hub and tip if desired. About the only constraint on blade design is that the tips of the blades do not interfere with each other near the center of the tunnel when they are rotated through differing pitch angles. Other variations in blade design for particular application will be apparent to one skilled in the art.

In order to minimize disturbance of water flow through the tunnel when the blades are changed in position, the central region of the movable tunnel wall portion 16 is made in the form of a zone of a spherical surface; that is, the inside surface 34 is a zone of a sphere having its center at the intersection of the centerline of the tunnel and the plane in which the axes of rotation of the blade support plates 31 lie. The intersections 36 between the spherical surface 34 and the cylindrical inside surface of the tunnel wall lie in planes parallel to the plane in which the axes of rotation of the blades lie and are equidistant from the center of the sphere. This spherical zone continues across the inside face of the blade support plates 31 so that no matter how the plates are rotated in order to change the pitch of the blades, the shape of the tunnel wall remains the same. This assures that water flow through the tunnel follows a smooth path and there are a mimimum of sharp discontinuities for cavitation and other disturbing phenomena. Although shown in the drawing as a sharp transition, it will be apparcnt that the boundary of the spherical zone may be faircd into the straight tunnel wall for minimum flow disturbance. The region where the thruster is mounted may also have a substantially larger diameter than other portions of the tunnel.

To obtain optimum thrust from the thruster, it is preferred that the pitch or angle of attack of the plurality of blades 21 be changed in synchronism so that all have the same pitch. Therefore, a single mechanism for controlling pitch of the blades is desirable. Such pitch control is obtained by means of a pin 37 extending from the base of each blade support plate 31 on the opposite side thereof from the spherical surface 34. That is, the pins 37 are within the gear case. The pin 37 on each of the blade supporting plates is displaced from the centerline of the circular plate. This eccentric mounting of the pin on the plate permits control of the angular position of the plate merely by displacing the pin to one side or the other, that is in a direction normal to the plane at which the axes of pivotal movement of the plate support plates may occur.

To move the pins 37 on the four blade support plates in synchronism, a slotted control ring 38 is provided surrounding the movable portion 16 of the tunnel wall. In the embodiment illustrated in FIG. 3, four helical slots 39 are formed on the inside face of the slotted ring 38, one of the helical slots 39 engaging each of the pins 37 on the blade support plate. Assuming for the moment that the movable tunnel wall section 16 is stationary, it will be seen that rotation of the slotted ring 38 about the centerline of the tunnel will cause the slots 39 to cam the pins 37 into new positions along the length of the tunnel. This shift in position of the pin along the length of the tunnel cause an angular change in position of the blade supporting plate 31 and hence a change in pitch of the blade.

The movable portion 16'of tunnel wall rotates about the tunnel axis during operation of the thruster and the slotted control ring 38 rotates therewith in order to maintain the four blades in their controlled pitch position. To change the pitch of the blades during operation with the tunnel wall and slotted ring rotating together, it is, in effect, necessary to change the phase angle of rotation of these two movable parts. Assuming, for example, that the slotted ring and tunnel wall portion 16 are rotating together with the control ring in a position wherein the blades 21 are in their neutral position, it will be seen that advance of the slotted ring relative to the tunnel wall portion will cam the blades in one direction and retardation of the s/oted ring relative to the tunnel wall portion will cam the pitch of the blades in an opposite direction. This is analogous to electrical phase shift. The amount of phase shift between the slotted ring and movable wall portion in order to obtain full change of blade pitch from one extreme to the other is not large since the helical slots 39 have a relatively steep pitch.

In order to keep the slotted ring 38 rotating with the movable tunnel wall portion 16, a driving interconnection is required and a differential driving connection is needed in order to obtain the needed phase shift of the slotted ring. The geared interconnection between the rotating tunnel wall portion and the slotted ring is illu trated in FIG. 3 and is also shown schematically inFIG. 4. In the schematic illustration in FIG. 4, arrows are provided indicating the direction of rotation of the vari ous mechanical elements. Exaggerated shaft lengths are illustrated in the schematic of FIG. 4 solely for purposes of illustration and it will be apparent that much closer connection is actually employed.

The phase shifting gear arrangement includes a peripheral spur gear 41 on the rotating tunnel wall portion 16, which in the illustrated embodiment comprises the driving member and the slotted control ring 38 is the driven member A similar peripheral spur gear 42 is provided on the slotted ring 38. A smaller spur gear 43 engages the peripheral spur 41 on the rotating tunnel wall portion and is directly connected to a driving bevel gear 44. The driving bevel gear 44 engages an idler bevel gear 46 in a differential mechanism. The idler gear 46 is also in engagement with a second bevel gear 47 which is driven thereby. The driven bevel gear 47 is directly connected to a spur gear 48 which rotates therewith. This driven spur gear 48 is in engagement with a pinion 49 (not seen in FIG. 3) directly connected to a like pinion 50 which is in engagement with the peripheral spur 42 on the slotted ring 38. The purpose of the pair of pinions 49 and 50 is to obtain the proper direction of rotation of the slotted ring relative to the tunnel wall portion. The gear ratio through the differential driving train is selected so that the slotted ring is driven at the same rotational speed as the tunnel wall portion 16. Other equivalent gearing arrangements will be apparent to one skilled in the art.

In order to advance or retard the slotted ring relative to the rotating tunnel wall portion, the idler differential gear 46 s employed. This idler bevel gear 46 is mounted on a bearing 52 (FIG. 4) that permits pivoting of the idler gear about the axis of rotation of the bevel gears 44 and 47 with which it is engaged. Means are provided for shifting the idler gear 46 about this axis on the bearing 52. In the schematic illustration of FIG. 4 a simple manual handle 53 is provided and despite relatively large driving forces, this can be adequate. The manual system is, however, employed in this illustration merely for purposes of exposition and it is preferred that some conventional mechanical means be provided for moving the idler gear 46. When the idler gear is tilted about the bearing 52, the phase angle between the driven bevel gear 47 and driving bevel gear 44 is shifted and this phase shift is carried through the subsequent driven gear train to shift the phase of the slotted control ring 38.

During operation of the tunnel thruster, power is applied thereto by way of the drive shaft 18 which drives the movable tunnel wall portion 16 through the bevel gears 27 and 28. This is typically driven at relatively constant speed and in a single direction of rotation. Only torque and power need be changed as thrust changes. Because of the differential gearing hereinabove described and schematically illustrated in FIG. 4, the slotted ring 38 rotates with the tunnel wall portion and holds the inwardly extending blades 21 in a fixed pitch position. This selected position controls the magnitude of thrust exerted by the blades as well as the direction of thrust. When it is desired to change the magnitude or direction of thrust, the idler gear 46 in the differential is shifted thereby changing the phase of the slotted ring relative to the rotating tunnel wall portion. This phase shift cams the pins 37 in the helical slots 39 thereby changing the pitch of the blades and changing the thrust exerted thereby without any change in either the speed or direction of rotation of the tunnel wall portion of the mechanism driving the tunnel wall portion. This permits rapid changes in the magnitude of thrust exerted by the thruster or even changes a direction of thrust in a short time since change in the direc tion of rotation of the heavy machinery is not required.

The ring type propeller with variable pitch is particularly advantageous as compared with a hub mounted propeller having controllable pitch. IN a propeller the outward ends or tips of the blades move most rapidly and thereby encounter and displace the largest proportion of the water. Stresses are high at the root of the blades in a hub mounted propeller since the blades are cantilevered outwardly. The tips of the blades are therefore deflected a substantial distance during operation from their no load" position. In a hub mounted propeller rapid changes of pitch cannot be effected because of substantial tip deflections.

In a ring type propeller, on the other hand, the tips are supported at the periphery and there is no deflection. The ends of the blades near the center of the tunnel are only lightly loaded and there deflection is considerably smaller that would be the case for a hub mounted propeller at the same speed. Since the tips of the blades are stabilized, rapid changes and reversals of pitch can be made at high rotational speeds. In a trasverse tunnel thruster this enhances the ability of the ship to maintain a controlled position. Another benefit lies in use of light blades in the ring propeller than in a conventional propeller.

FIG. 5 illustrates in a view substantially similar to that of FIG. 3, another means for controlling the pitch of the propeller blades. As illustrated in this embodiment, the fixed tunnel wall comprises a ring 122 forming one end wall of a gear case 117. The balance of the gear case is formed on another fixed ring 124 and these two rings are bolted to the balance of the fixed tunnel wall for ready replacement in substantially the same manner as herinabove described in relation to FIG. 3.

A movable tunnel wall portion 116 is mounted for rotation in the fixed tunnel wall portion on ball bearings 126. A drive shaft 118 drives a bevel gear 128 which engages a bevel gear 127 on the movable tunnel wall portion for driving the entire mechanism in rotation. Mounted in the rotatable tunnel wall portion 116 are a plurality of blade-supporting plates 131, only one of which is illustrated in FIG. 5. The blade-supporting plates 13] are mounted on ball bearings 132 for rotation for changing thev pitch of thruster blades 121 mounted thereon. In order to control the pitch of the thruster blades 121, a pin 137 is formed on the outer side of the blade-supporting plate 131 and eccentric from the axis of rotation of the blade-supporting plate. Control of the pitch is obtained by a slotted control ring 61 extending peripherally around the rotatable tunnel wall portion 116. Other aspects of the rotating tunnel wall portion 116 and its driving mechanism are similar to that illustrated hereinabove in FIG. 3.

Theblades 121 are somewhat different from those described and illustrated in FIG. 3 in that they are interconnected at thier adjacent ends along the centerline of the thruster tunnel. The blades 21 illustrated in FIG. 3, are cantilevered outwardly from the bladesupporting plates 31 (that is, inwardly towards the tunnel centerline) and their adjacent tips are free which can lead to tip losses and cavitaton may occur under some conditions. In the embodiment illustrated in FIG. 5, the tips of the blades 121 are each rotatably connected to a hub 62 by end pins 60 on the centerline of a thruster tunnel. The hub 62 is symmetrical to present the same configuration when the thruster is employed for propulsion to either port or starboard. in the illustrated embodiment, it is connected only to the tips of the blades 121 and rotates therewith. However, if desired, a supporting strut or struts can be provided to the fixed tunnel wall for supporting the hub and permitting it to remain fixed or to rotate as may be desired. By permitting it to rotate, problems of remote lubrication are minimized.

The hub 62 changes the stress patterns in the interconnected blades 121 as compared with the stress patterns in the cantilevered blades 21 described and illustrated in FIG. 3, and further, the hub avoids any problems that may arise due to tip losses along the centerline of the thruster tunnel. The hub is formed with at least a central portion in the form of a spherical surface so that variations in pitch of the blades do not change the shape of the hub and cause changes in water flow pattern thereabout except as influenced by the blades themselves. Preferably, a smooth transition is provided at the leading and trailing edges of the hub for smooth hydrodynamic flow.

The slotted ring 61 provided for controlling pitch of the blades 121 is different from the slotted ring 38 illustrated in H0. 3. The slotted ring 61 is provided with a circumferentially extending, inwardly directed slot 63 which engages the pins 137 on the several bladesupporting plates 131. The slotted control ring 61 remains fixed in rotational position as the rotating tunnel wall portion 116 rotates and therefore, if desired, a low friction bearing (not illustrated) is preferably provided between the pins 137 and the walls of the slot 63.

In order to change the pitch of the blades, the position of the slotted ring 61 is shifted along the length of the tunnel thereby camming the pins 137 and changing the pitch of the blades. Shifting of the control ring 61 is provided by three or more evenly spaced radial projections 64 (one of which is seen in FIG. each of which is engaged by a conventional lead screw 66. Each of the lead screws has a pinion 67 at one end and these pinions are engaged by an internal ring gear 68 extending aroud the inside of the gear case. Rotation of the ring gear by any conventional means (not shown) either mechanically driven or driven by hand, causes rotation of the pinion gear 67 and hence lead screw 66. This advances or retracts the projections 64 and hence the entire slotted ring 61, thereby camming the pins 137 and changing the pitch of the blades.

Although limited embodiments of controllable pitch tunnel thruster have been described and illustrated herein, many modifications and variations will be apparent to one skilled in the art. Thus, for example, differential gearing or other means for shifting a slotted ring relative to the movable tunnel wall portion may be providdd to one side of the rotatable portion of the mechanism rather than peripherally surrounding it. By providing such a mechanism to one side, the surrounding portion is left accessible and can be fitted with a rotor portion of an electric motor directly connected to the rotatable tunnel wall portion. An electric motor stator can then surround the rotor and direct electrical drive of the movable tunnel wall portion can be obtained. Although the embodiments described and illustrated herein have employed projecting pins on the blade-supporting plates and a slotted ring, the complement of this can also be employed wherein projections on the ring engage a suitable camming member on the blade'supporting plate. Many other modifications and variations will be apparent to one skilled in the art and it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described.

What is claimed is:

1. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising:

a fixed tunnel wall;

a movable portion of tunnel wall;

means for mounting the movable portion for rotation about the tunnel axis;

means for driving the movable portion of tunnel wall;

a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; and

means for controlling pitch of the blades relative to a plane transverse to the tunnel axis comprising:

a ring around the movable tunnel wall portion;

means interconnecting each of the inwardly extending blades to the ring for controlling pitch in response to ring position;

means for changing the position of the ring relative to the movable tunnel wall portion;

a blade-supporting plate connected to each blade;

means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tune! axis;

a pin mounted eccentrically on each of the bladesupporting plates; and

a camming slot extending helically on the ring engaging each of the pins; and wherein the means for changing position comprises means for shifting phase of rotation of the ring relative to rotation of the movable tunnel wall portion.

2. In an improved thrust controlling and reversing apparatus as defined in claim 1, means for shifting phase of rotation comprising:

a driving gear on the movable tunnel wall portion;

a driven gear on the ring; and

a differential gear interconnection between the driving gear and the driven gear.

3. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising:

a fixed tunnel wall;

a movable portion of tunnel wall;

means for mounting the movable portion for rotation about the tunnel axis;

means for driving the movable portion of tunnel wall;

a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; and

means for controlling pitch of the blades relative to a plane transverse to the tunnel axis comprising:

a ring around the movable tunnel wall portion,

means interconnecting each of the inwardly extending blades to the ring for controlling pitch in response to ring position,

means for changing the position of the ring relative to the movable tunnel wall portion,

a blade-supporting plate connected to each blade,

means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis,

a pin mounted eccentrically on each of the bladesupporting plates; and

a camming slot in the ring engaging each of the pins; and

an internal surface on the movable tunnel wall portion in the form of a zone of a spherical surface; and wherein the blade-supporting plates have an internal surface in the form ofa continuation of the zone ofa spherical surface.

4. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising:

a fixed tunnel wall;

a movable portion of tunnel wall;

means for mounting the movable portion for rotation about the tunnel axis;

means for driving the movable portion of tunnel wall; a plurality of bladesextending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis;

a blade-supporting connected to each blade, the surface of the blade-supporting plate being substantially a continuation of the internal surface of the movable tunnel wall portion;

means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis; and

means for synchronously rotating the blade-support plates for changing pitch of the blades relative to a plane transverse to the tunnel axis.

5. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising:

a fixed tunnel wall;

a movable portion of tunnel wall;

means for mounting the movable portion for rotation about the tunnel axis;

means for driving the movable portion of tunnel wall;

a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis;

an internal surface on the movable tunnel wall portion in the form of a zone of a spherical surface;

a blade-supporting plate connected to each blade,

each of the blade-supporting plates having an internal surface in the form of a continuation of the zone of a spherical surface;

means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis; and camming means for synchronous rotating the bladesupporting plates for changing pitch of the blades relative to a plane transverse to the tunnel axis.

6. In an improved thrust controlling and reversing apparatus as defined in claim 5, an improved means for rotating the blade support plates comprising:

a ring around the movable tunnel wall portion and rotatable therewith;

camming means interconnecting each of the blade support plates and the ring for camming rotation of the blade support plates in response to shift of the phase of rotation of the ring relative to rotation of the movable tunnel wall portion.

7. In an improved thrust controlling and reversing apparatus as defeind in claim 6, improved means for shifting phase of rotation comprising:

a driving gear around the movable tunnel wall portion;

a driven gear around the ring; and

a differential gear interconnection between the driving gear and driven gear.

* k I I i 

1. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising: a fixed tunnel wall; a movable portion of tunnel wall; means for mounting the movable portion for rotation about the tunnel axis; means for driving the movable portion of tunnel wall; a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; and means for controlling pitch of the blades relative to a plane transverse to the tunnel axis comprising: a ring around the movable tunnel wall portion; means interconnecting each of the inwardly extending blades to the ring for controlling pitch in response to ring position; means for changing the position of the ring relative to the movable tunnel wall portion; a blade-supporting plate connected to each blade; means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis; a pin mounted eccentrically on each of the blade-supporting plates; and a camming slot extending helically on the ring engaging each of the pins; and wherein the means for changing position comprises means for shifting phase of rotation of the ring relative to rotation of the movable tunnel wall portion.
 2. In an improved thrust controlling and reversing apparatus as defined in claim 1, means for shifting phase of rotation comprising: a driving gear on the movable tunnel wall portion; a driven gear on the ring; and a differential gear interconnection between the driving gear and the driven gear.
 3. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising: a fixed tunnel wall; a movable portion of tunnel wall; means for mounting the movable portion for rotation about the tunnel axis; means for driving the movable portion of tunnel wall; a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; and means for controlling pitch of the blades relative to a plane transverse to the tunnel axis comprising: a ring around the movable tunnel wall portion, means interconnecting each of the inwardly extending blades to the ring for controlling pitch in response to ring position, means for changing the position of the ring relative to the movable tunnel wall portion, a blade-supporting plate connected to each blade, means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis, a pin mounted eccentrically on each of the blade-supporting plates; and a camming slot in the ring engaging each of the pins; and an internal surface on the movable tunnel wall portion in the form of a zone of a spherical surface; and wherein the blade-supporting plates have an internal surface in the form of a continuation of the zone of a spherical surface.
 4. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising: a fixed tunnel wall; a movable portion of tunnel wall; means for mounting the movable portion for rotation about the tunnel axis; means for driving the movable portion of tunnel wall; a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; a blade-supporting connected to each blade, the surface of the blade-supporting plate being substantially a continuation of the internal surface of the movable tunnel wall portion; means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis; and means for synchronously rotating the blade-support plates for changing pitch of the blades relative to a plane transverse to the tunnel axis.
 5. In a ship with a transverse thrust tunnel, an improved thrust controlling and reversing apparatus comprising: a fixed tunnel wall; a movable portion of tunnel wall; means for mounting the movable portion for rotation about the tunnel axis; means for driving the movable portion of tunnel wall; a plurality of blades extending inwardly from the movable portion of tunnel wall and connected for rotation therewith about the tunnel axis; an internal surface on the movable tunnel wall portion in the form of a zone of a spherical surface; a blade-supporting plate connected to each blade, each of the blade-supporting plates having an internal surface in the form of a continuation of the zone of a spherical surface; means for mounting each of the blade-supporting plates in the movable tunnel wall portion for rotation about an axis transverse to the tunnel axis; and camming means for synchronous rotating the blade-supporting plates for changing pitch of the blades relative to a plane transverse to the tunnel axis.
 6. In an improved thrust controlling and reversing apparatus as defined in claim 5, an improved means for rotating the blade support plates comprising: a ring around the movable tunnel wall portion and rotatable therewith; camming means interconnecting each of the blade support plates and the ring for camming rotation of the blade support plates in response to shift of the phase of rotation of the ring relative to rotation of the movable tunnel wall portion.
 7. In an improved thrust controlling and reversing apparatus as defeind in claim 6, improved means for shifting phase of rotation comprising: a driving gear around the movable tunnel wall portion; a driven gear around the ring; and a differential gear interconnection between the driving gear and driven gear. 